CO Detection

Carbon Monoxide (CO) Detection
CO can be detected with CO detectors that meet the requirements of Underwriters Laboratories (UL) standard 2034.
Concentrations
Since the toxic effect of CO is dependent upon both CO concentration and length of exposure, long-term exposure to a low concentration can produce effects similar to short term exposure to a high concentration.

Detectors that meet the UL standard measure both high CO concentrations over short periods of time and low CO concentrations over long periods of time. The effects of CO can be cumulative over time.

Detectors sound an alarm before the level of CO in a person's blood would become crippling.

Price
Detectors that meet the UL 2034 standard currently cost $35 - $80. There are inexpensive cardboard or plastic detectors that change color and do not sound an alarm and have a limited useful life. They require the occupant to look at the device to determine if CO is present. CO concentrations can build up rapidly while occupants are asleep, and these devices would not sound an alarm to wake them.

Installation
CO gases distribute evenly and fairly quickly throughout the house. Therefore, a CO detector should be installed on the wall or ceiling in sleeping area(s) but outside individual bedrooms to alert occupants who are sleeping.

Appliances
Vent safety shutoff systems have been required on furnaces and vented heaters since the late 1980s. They protect against blocked or disconnected vents or chimneys.

ODS Devices
Oxygen depletion sensors (ODS) have also been installed on un-vented gas space heaters since the 1980s. ODS protect against the production of CO caused by insufficient oxygen for proper combustion.

These devices (ODSs and vent safety shutoff systems) are not a substitute for regular professional servicing, and many older, potentially CO-producing appliances may not have such devices. Therefore, a CO detector is still important in any home as another line of defense.